Several reports have been made on chelate resins having high-molecular compound ligands capable of forming a complex with a heavy metal ion. Commercially available chelate resins having an iminodiacetate group include Dowex A-1 (Dow Chemical Co.), Diaion CR-10 and 20 (Mitsubishi Chemical Industries Limited), and UNICELLEX UR-10, 20 and 30 (UNITIKA Ltd.). But these resins possess a very low selectivity for adsorbing metal ions, especially uranium ions. Many studies have been made on chelate resins having a phosphonate group. For example, Zh. Anal. Khim., Vol. 28, p. 2324, 1973 discloses a chelate resin having phosphonate and iminodiacetate residues, and Anal. Chem., Vol. 46, p. 489, 1974 discloses a chelate resin having phosphonate and alcohol residues. The disclosed resins having a phosphonate group still do not possess satisfactorily high selectivity for uranium ions and have proved virtually useless in recovering uranium from sea water and from crude phosphoric acid solutions used for fertilizer. Zh. Anal. Khim., Vol. 29, p. 1284, 1974 discloses a styrene chelate resin of the iminodiethylene phosphonic acid type together with data on its selective adsorption of uranium ion. But the production of iminodiethylene phosphonic acid used as a starting material for the reported resin is expensive and involves a long and complex process. Hence, the resin is practically unsuitable for use in industry.